Being different from a conventional client/server mode, there is not a central server node in a peer-to-peer (P2P) network. Each node may be used as the server to provide services for other nodes, and may also enjoy the services provided by other node serving as the server. Therefore, in the P2P network, all nodes are equal in position, and each node is referred to as a peer.
The P2P network is a self-organized configuration network system. In the network, the behaviors of joining the network or exiting the network performed by each Peer are random. Similarly, in the network, for the communication between each two Peers, after a relevant Key is found according to logical distributed hash table (DHT), a lower layer physical link is randomly selected to perform the route connecting communication. In this manner, when the number of the Peers or the communication amount in the network gradually increases, the flow in the whole network is unorganized and out of order, and a great amount of data interaction is performed through a whole network search or operation. Finally, a backbone network with an insufficient bandwidth source and an inter-domain link are seriously consumed, thereby generating congestion.